Scroll type fluid displacement apparatus are well known in the prior art. For example, U.S. Pat. No. 801,182 issued to Creux discloses such an apparatus which includes two scrolls, each having a circular end plate and a spiroidal or involute spiral element. The scrolls are maintained angularly and radially offset so that both spiral elements interfit to form a plurality of line contacts between their spiral curved surfaces to thereby seal off and define at least one pair of fluid pockets. The relative orbital motion of the two scrolls shifts the line contacts along the spiral curved surfaces and, as a result, the volume of the fluid pockets increases or decreases, dependent on the direction of the orbital motion. Thus, a scroll type fluid displacement apparatus may be used to compress, expand or pump fluids.
Furthermore, U.S. Pat. No. 4,560,330 to Murayama et al., for example, discloses a hermetic scroll compressor which includes a compression mechanism having a fixed scroll, an orbiting scroll associated with a rotation preventing device, and a driving mechanism therefor in one sealed container. In this hermetic type scroll compressor, the essentially inseparable container is hermetically sealed, for example, by welding, so that leakage of refrigerant from the container is prevented. While the above mentioned hermetically sealed scroll compressor prevents leakage of refrigerant from the container, it can be disassembled only by destructively opening the sealed container to, for example, repair, adjust or exchange internal parts. Furthermore, it is virtually impossible to dynamically test the compression and drive mechanismms before assembling the compressor components into the sealed container. Therefore, compressors found to be functionally defective after assembly thereof, often become scrap in view of the repair factors which may render repair cost-ineffective.